The U.S. Food and Drug Administration approved the first ‘new’ kind of depression drug since Prozac came to the market in 1988. Spravato (esketamine) nasal spray, in conjunction with an oral antidepressant, is for the treatment of depression in adults who have tried at least two other antidepressant treatments but have not benefited from them (treatment-resistant depression). That means about 5 million of the 16 million people in the U.S. with major depression might benefit from esketamine, said Courtney Billington, president of Janssen Neuroscience, a unit of Johnson & Johnson.

Esketamine presents some challenges because of its similarities to ketamine. In high doses, both drugs can cause sedation and out-of-body experiences. And ketamine, often called Special K in its illicit form, has become a popular party drug. Because of potential for abuse, the patient self-administers Spravato nasal spray under the supervision of a health care provider in a certified doctor’s office or clinic, and the spray cannot be taken home.

Esketamine’s approval comes as more and more doctors have begun administering a generic version of ketamine for depression. Generic ketamine is approved as an anesthetic, not as an antidepressant. Even so, doctors can legally prescribe it for off-label medical uses.

And as a growing number of studies have shown ketamine’s effectiveness against depression, ketamine clinics have sprung up around the United States. These clinics often administer the drug in an intravenous infusion.